Host Diversity of Beauveria Bassiana (Balsamo) Vuillemin on Rice Field in Bolaang Mongondow Regency

Beauveria bassiana can attack a variety of hosts and their virulence can vary at each host and location. Exploration of the diversity of hosts B. bassiana from local isolates needs to be done as initial information that can explain the ability of B. bassiana in infecting insects. Sampling locations were selected in three district, each district selected three stations and each station consisted of 10 plots. The location of sampling is determined by the purposive random sampling method. Each station was made a plot measuring 1m x 1m and distributed randomly. Every insect infected with B. bassiana was taken and taken to a laboratory for identification. The results showed that there were five insects that hosted B. bassiana, namely Nilaparvata lugens, Scotinophara coarctata, Leptocorisa oratorius, Nezara Viridula and Paraeucosmetus pallicornis. The highest host diversity index was found in North Dumoga with a value of 1.47. The highest abundance index was found in N. lugens host in East Dumoga with a value of 43%. The highest density was found in the host N. lugens in Central Dumoga with a value of 1.93 ind / m2. There were indications of differences in virulence of the B. bassiana local isolates that were influenced by the spesies of host and location. Akta Agrosia


INTRODUCTION
Rice ecosystems can be an ideal source of entomopathogenic fungi. As reported by Rosmini and Lasmini (2010) there were five entomopathogenic fungi that attacked the green leafhopper (Nephotettix viresens) in rice field in Donggala Regency, one of which was Beauveria sp. Exploration of entomopathogenic fungi in rice cultivation needs to be done to provide biological agents that can replace the role of synthetic pesticides (Rizal et al. 2017).

Bolaang Mongondow Regency, North Sulawesi
Province is a center of rice production that experiences various pest attacks (Mandei et al., 2011;Kila et al., 2016;Kanakan et al., 2017). Naturally, planting sites in this region must contain entomopatogenic fungi that are usually associated with rice pest insects. Exploration of local entomopathogenic fungi can be an environmentally friendly pest control alternative. One of the entomopathogenic fungi that is promising to be utilized is B. bassiana.
Fungi B. bassiana is one of the entomopathogenic fungi that has been known its effectiveness as a plant pest control (Anggarawati et al., 2017). This color of fungus colonies at in vitro media is white flour. The colonies will turn yellowish or reddish after aging (Effendy et al., 2010). B. bassiana has been known to attack several species of insects, both pest insects, disease vector insects, and other insects. Previous work of Priyatno et al. (2016) showed that B. bassiana attacked stinky bugs (Leptocorisa oratorius), black ladybugs, and brown stem plant hopper (Nilaparvata lugens). According to Valero-Jiménez et al. (2014) this entomopathogen have also been used to control Anopheles coluzzii mosquitoes, a vector for malaria. Mwamburi et al. (2015) reported that B. bassiana could be used to control house flies (Musca domestica). B. bassiana was also reported to attack crickets (Gryllus sp.) (Ardiyati et al., 2015).
The virulence of B. bassiana has been known to vary depending on the origin, genetic diversity, the stage of the insect and the host. Valero-Jiménez et al. (2016) reported that there were several genes and molecular processes that could influence the virulence of B. bassiana against mosquitoes. Huang et al. (2019) reported that B. bassiana had different virulence qualities at each stage of Haemaphysalis longicornis. In India Bhadauria et al. (2013) reported no correlation between B. bassiana virulence and host insect origin. However, in China, Li et al. (2014) reported that B. bassiana isolates had different virulence at each host and each location.
Based on this information it can be seen that B. bassiana can attack various hosts and their virulence can vary at each host and location. For this reason, a preliminary study on the diversity of B. bassiana hosts originating from local isolates, Bolaang Mongondow Regency needs to be done. This study aims to analyze the diversity, abundance, and density of host insects infected by B. bassiana local isolates.

MATERIALS AND METHODS
The study was conducted from April 2019 to February 2020 in Bolaang Mongondow Regency, North Sulawesi. Three sub-districts were taken as sample locations and three stations were made as replications in each sub-district. Station selection was carried out using a purposive random sampling method based on rice age.
Each station was made with a plot size of 1m x1 m, 10 plots were distributed randomly. All fungal-infected insects were collected and then were identified and selected at the Laboratory of Biological Agents, Center for Plant Protection and Horticulture, North Sulawesi Agriculture and Animal Husbandry Office.
Host diversity index was calculated using the Shannon-Wiener Diversity Index (Stilling, 2012).
with the total number of whole individuals (N) s = The number of species in the sample The Host Abundance Index was calculated using the Abundance Index according to Fachrul (2007).
Host Density Index was calculated using the Density Index according to Stilling (2012).

Exploration of the host B. bassiana
The exploration showed that insects infected with B. bassiana were found in each district. Five species of host insects infected with B. bassiana were found in all district. The host insects were Nilaparvata lugens, Scotinophara coarctata, Leptocorisa oratorius, Nezara viridula, and Paraeucosmetus pallicornis. Data from Central Dumoga, North Dumoga, and East Dumoga showed that the highest infected B. bassiana insect was N. lugens with successive values of 1.93, 1.40, 1.07 and the lowest was N. viridula with successive values i.e. 0.20, 0.17, and 0.07 (Table 1).
Insects found infected with B. bassiana were common insect pests found in the rice ecosystem. N. lugens was one of the main pests of rice that is plastic which was easy to adapt to the environment and attacked the plant by sucking the liquid stem to dry (Nurbaeti et al., 2010). S. coarctata was a pest that caused huge losses in rice plantations because it attacked almost all stages of rice growth (Sepe and Demayo, 2017). L. oratorius is an important pest of rice because its presence can cause yield losses. Generally these pests attack at generative growth in rice (Kartohardjono et al., 2009). N. viridula is a pest that is commonly found in Legumes (CABI, 2016). This pest is an important pest in rice plants which causes considerable damage and is detrimental to the economy (Jones, 1988). P. pallicornis was a new pest since the 1980s that caused damage in rice plants in Bolaang Mongondow which had been watched out (Sembel, 2014).

Diversity Index of B. bassiana Host (H')
Diversity index of B. bassiana host varied among district. The highest value was found in North Dumoga District (H'=1.47), followed by Central Dumoga District (H'=1.45), with the lowest was found in East Dumoga District (H'=1.38) (Figure 1).
The H' value obtained indicated that the diversity of host B. bassiana in all district was considered to be in the medium category (Alikodra, 2002

Central-Dumoga
North Dumoga East Dumoga the evenness of the number of individuals between species rather than on richness per species. So the high or low value of the diversity index depends on the evenness between species (Solle, et al., 2017). This indicated that the difference in the number of fungal infections between hosts in the District of North Dumoga was not large because it had the highest diversity index, which was proportionally inversed to the District of East Dumoga. The low diversity index value indicated the difference in the number of infections between hosts was very large when compared to the other two districts.

Abundance Index of Host B. bassiana
The results showed that B. bassiana was abundant in N. lugens host in all district with the following values; Central Dumoga District 34%, North Dumoga District 32%, and East Dumoga 43% ( Table 2).
The high abundance of B. bassiana in N. lugens showed that these hosts were most often attacked by B. bassiana. This could possibly be caused by the population size of the pest (N. lugens) being quite high. According to Mardiana (2018) and Chandra (2019) population size can affect the spread of pathogens. In this case the greater the size of the N. lugens population, the more individuals in this population were infected by B. bassiana. The phenomena was found on N. viridula, the abundance of B. bassiana in these insects were very low, ranging from 3 -4%. This showed that the population N. viridula was very low in rice plants in the three districts.
The Abundance Index obtained explains the high and low values of the diversity index. As mentioned earlier that the difference in the number of individuals between species can affect the value of the diversity index obtained. The difference in the number of species between infected species in North Dumoga was low. The difference in the value of the abundance index between N. lugens (32%) and L. oratorius (25%) was 7%. The difference in value of abundance index between N. lugens (32%) and S. coarctata (18%) was14% and the difference in value of abundance index N. lugens (32%) with N. viridula (4%) was 28%, these were what causing the high value of diversity in the North Dumoga District. The opposite result was found in East Dumoga District where the difference between the abundance index values of N. lugens (43%) and S. coarctata (22%) was 21%. The difference in the value of abundance index of N. lugens (43%) with L. oratorius and P. pallicornis (16%) was 27%, while the difference in the value of abundance index of N. lugens (43%) with N. viridula (3%) was 40%. The difference in the index of abundance among different spesies of hosts was very large in East Dumoga, this caused the value of the diversity index in this area to be the lowest compared to the other two districts.

Density Index of B. bassiana Based on Its Host
Density Index in all district showed that N. lugens insects had the highest density per m 2 . Successively from the District of Central Dumoga, North Dumoga, and East Dumoga, the values were as follows; 1.93 ind/m 2 , 1.40 ind/m 2 , 1.07 ind/m 2 ( Table 3).
The Density Index describes the population size in an area that is affected by the habitat area and the number of similar individuals found in the area (Suin, 2003). Based on the data obtained showed that the largest population size was in Central Dumoga where the largest population was found in the population of N. lugens followed by S. coarctata, P. pallicornis, L. oratorius and N. viridula. In North Dumoga the largest population was found in N. lugens followed by L. oratorius, P. pallicornis, S. coarctata, and N. viridula. In East Dumoga the largest population was N. lugens followed